We wish to examine the adaptation of synaptic events to changing neural inputs and external environments. We are focussing on catecholamines because of the important role of these systems in the central and pheripheral controls of homeostasis. During the past year we have made the following observations: (1) The effect of prior in vitro phosphorylation on tyrosine hydroxylase (TH) activity in crude brain homogenates is strongly influenced by assay pH and brain region. (2) The effects of haloperidol on dihydroxyphenylacetic acid (DOPAC) levels and TH activity are strongly correlated. (3) Destruction of dopamine (DA) containing nerve terminals in brain increases the neurological impairments proposed by acute glucoprivation. (4) Such lesions also increase the ratio of DOPAC to DA in striatum and reduce the impact of neuroleptics on that ratio. During the coming year we will be expanding on these observations. In addition, we will begin to develop a peripheral model for studying the impact of regulatory challenges on catecholaminergic function in intact and lesioned animals.